1. Field
Subject matter disclosed herein relates to a memory device, and more particularly to read performance of phase change memory.
2. Information
Phase change memory (PCM) may operate based, at least in part, on behavior and properties of one or more particular phase change materials, such as chalcogenide alloy and/or germanium antimony telluride (GST), just to name a few examples. Crystalline and amorphous states of such materials may have different electrical resistivities, thus presenting a basis by which information may be stored. An amorphous, high resistance state of such materials may represent a stored first binary state and a crystalline, low resistance state of such materials may represent a stored second binary state. Of course, such a binary representation of stored information is merely an example: PCM may also be used to store multiple memory states, represented by varying degrees of phase change material resistivity, for example.
A PCM cell may transition from an amorphous state to a crystalline state by applying a bias signal to the memory cell. Characteristics of a bias signal, such as peak magnitude and/or pulse width, for example, may be selected to allow a transition to a crystalline state. Reading a state of a PCM cell may be performed by applying a bias current or voltage to the PCM cell to detect the cell's resistivity.
Over time, various parameters of a PCM cell may drift or change as a result of changing PCM temperature, re-crystallization of phase change material, drift, and/or cycling, just to name a few examples. Such effects may lead to read errors of the PCM cell.